Immunological Adjuvant Effect of Ginsenoside Rh 4 from the Roots of Panax notoginseng on Specific Antibody and Cellular Response to Ovalbumin in Mice

Ginsenoside Rh 4 ( 1 ), a saponin isolated from the roots of Panax notoginseng ( Burk .) F. H. Chen , was evaluated for its haemolytic activity and adjuvant potential on specific antibody and cellular response to ovalbumin (OVA) in mice. Compound 1 showed a slight haemolytic effect, its concentration inducing 50% of the maximum haemolysis ( HD 50 value) being 407±12 μg/ml using a 0.5% suspension of red blood cells. Compound 1 significantly increased the concanavalin A (Con A)‐, lipopolysaccharide (LPS)‐, and OVA‐induced splenocyte proliferation in OVA‐immunized mice especially at a dose of 25 μg ( P <0.05, P <0.01, or P <0.001). The OVA‐specific serum IgG, IgG1, and IgG2b antibody levels were also significantly enhanced by 1 at a dose of 25 μg compared to the OVA control group ( P <0.05 or P <0.01). Moreover, the enhancing effect of 1 on the OVA‐specific IgG2b antibody responses to OVA in mice was more significant than that of Alum (Al(OH) 3 gel; P <0.01). These results suggest that 1 could be safely used as adjuvant with low or non‐haemolytic effect.